Contact device

ABSTRACT

Contact device comprising an electrically conductive contact spring clamped tight at one end, whereas its freely movable end is located opposite a countercontact, and comprising an energizing coil controlling the contact spring and having its field extending in the direction of length of the contact spring, which is provided at its movable part near the clamped end with at least one permanent magnet surrounded by the energizing coil and polarized transversely of the direction of length of the contact spring.

' United States Patent Van der Heide [54] CONTACT DEVICE [72] Inventor: Hendrik Van der Heide, Emmasingel,

Eindhoven, Netherlands [73] Assignee: U.S. Philips Corporation, New York, NY.

[22] Filed: Sept. 15, 1970 [2 1] Appl. No.: 72,363

[30] Foreign Application Priority Data Sept. 23, 1969 Netherlands ..69l4458 [52] U.S. Cl ..335/153 [51] lnt.Cl ...H0lh51/22,H0lh5l/28 [58] FieldofSearch ..335/l5l-l54, 86

[56] References Cited UNITED STATES PATENTS 2,264,022 ll/l94l Ellwood ..335/ 151X [4 1 Jan. 25, 1972 Lowry ..335/l54 X 3,166,652 Werts ..335/l 53 Primary ExaminerBernard A. Gilheany Assistant ExaminerR. N. Envall, Jr. Attorney-Frank R. Trifari [57] ABSTRACT Contact device comprising an electrically conductive contact spring clamped tight at one end, whereas its freely movable end is located opposite a countercontact, and comprising an energizing coil controlling the contact spring and having its field extending in the direction oflength of the contact spring, which is provided at its movable part near the clamped end with at least one permanent magnet surrounded by the energizing coil and polarized transversely of the direction of length of the contact spring.

4 Claims, 1 Drawing Figure CONTACT mzvrcs This invention relates to a contact device comprising at least one electrically conductive contact spring which is clamped tight at one end and having its other, freely movable end located opposite a countercontact, and at least one energizing coll controlling the contact spring and having its field extending in the direction-of length of the contact spring.

Known contact devices of the kind set forth frequently comprise two partly overlapping contact springs clamped tight in a hermetically closed envelope and made of magnetizable and electrically conductive material. The contact springs are closed by means of a coil surrounding the envelope and having its field traversing the contact springs and the contact aperture in series so that a force of attraction is produced between the freely movable ends of the contact tongues, which force is sufficiently great for closing the contact springs with the desired contact force. These known contact devices have the disadvantage that the desired contact force can be attained only with difficulty when the contact aperture is comparatively large. In view of the tendency to miniaturization it is an objection to use larger energizing coils. Larger energizing coils, moreover, give rise to an increase in price which is unacceptable in series manufacture. A further disadvantage resides in the fact that the force of attraction occurring during closure between the magnetized contact springs increases in value substantially in quadrature according as the aperture becomes smaller. Owing to the quadratically increasing force between the contact springs, they snap against each other with such a speed that bouncing of the contact springs may occur. A further disadvantage is thatthe contact springs have to be made of a good electrically conductive material which is readily magnetizable so that the number of suitable contact spring materials is drastically restricted.

An object of the invention is to obviate said disadvantages and to provide an improved magnetic contact device.

The invention is characterized in that the movable part of the contact spring is provided, near the clamped end, with at least one permanent magnet polarized transversely to the direction of length of the contact spring and adapted to be moved by the field of the energizing coil, said permanent magnet being arranged in the space surrounded by the energizing coil.

The invention will be described more fully with reference to the sole FIGURE of the accompanying drawing.

The FIGURE'shows schematically a longitudinal sectional view of one embodiment of a contact device in accordance with the invention.

The contact device 1 shown in the FIGURE comprises contact springs 3 and 5 composed of electrically conductive material. The contact springs 3 and 5 are clamped tight at the ends 7 and 9, respectively, in a hermetically closed envelope 11, whereas the other freely movable ends 13 and 15, respectively, form a contact gap 17. Near the clamped end 7 the contact spring 3 is provided on one side with a plate-shaped permanent magnet 19 and on the other side with an identical permanent magnet 21. The permanent magnets are polarized in the same direction transversely to the direction of length of the contact spring 3. Between the clamped end 7 and the permanent magnets 19 and 21 the contact spring 3 preferably has a readily flexible portion 23 in the form of a local constriction of the cross section of the contact spring. The portion of the hermetically closed envelope l1 accommodating the permanent magnets 19 and 21 is surrounded by an energizing coil 25. When the coil 25 is energized, a magnetic field is produced which is transverse to the permanent field of the magnets 19 and 21. Because the direction of polarization of the permanent magnets 19 and 21 is such that they tend to orientate to the coil field transverse of the direction of polarization, the contact spring 3 is subjected at the place of the pennanent magnets to a couple which remains substantially constant during bending.

Since, in contrast to the known contact devices, a quadratically increasing magnetic force of attraction is not produced between the free ends of the contact springs 3 and 5, the risk of bouncing is considerably reduced. Even if the contact springs 3 and 5 are made of magnetizable material, bouncing of the ends of the contact springs is avoided because the energizing coil, which only surrounds the permanent magnets 19 and 21, does not affect the ends of the contact springs. The established contact is interrupted by terminating the energization of the coil 25. The permanent magnets 19 and 21 are preferably arranged as closely as possible to the readily flexible portion 23 in order to minimize the path covered by the mass which moves during bending. It should be noted that the permanent magnets 19 and 21 may have such a shape that their common center of gravity is located at the readily flexible portion. This may be achieved by having the two magnets taper towards their sides facing the clamped end of the contact spring concerned, the planoparallel portions of the magnets being arranged as closely as possible to the readily flexible portion of the contact spring, while the tapering portions of the magnets freely project beyond the readily flexible portion of the contact spring. In contrast to the fairly small stroke in the known contact devices, the stroke in contact devices according to the invention is relatively large owing to the larger angular rotation of that portion of the bending contact spring which is located near the clamped part.

Contact devices according to the invention may be constructed in a symmetrical shape by providing the two contact springs with permanent magnets and by arranging two energizing coils in the manner described. Instead of providing a permanent magnet on either side of the contact spring, only one permanent magnet may be used. In this case, however, the construction of the contact device is asymmetrical. It is furthermore possible to construct a contact device according to the invention in the form of a make-and-break contact by providing two countercontacts, between which the freely movable end of the contact spring provided with the permanent magnets is located. In accordance with the polarization of the coil field the contact spring will establish a contact with one or with the other countercontact. The countercontacts may be stationary contacts or contact springs.

It'should finally be noted that a contact spring of a contact device according to the invention may be provided at its free end with a plug of contact material or with a sharp pin which are driven, for establishing the contact, against or into a powdery or liquid conductive material contained in a holder, which is fastened to the countercontact. This way of establishing a contact requires a comparatively large stroke of the free end of the contact spring. In contact devices according to the invention such a comparatively large stroke can be obtained in a simple manner.

What is claimed is:

l. A contact device comprising at least one electrically conductive contact spring clamped tight at one end and having its other freely movable end located opposite a countercontact, at least one energizing coil controlling the contact spring and having its field extending in the direction of length of the contact spring, at least one permanent magnet provided on the movable part of the contact spring near the clamped end and polarized transversely to the direction of length of the contact spring and adapted to be moved by the field of the energizing coil, said permanent magnet being arranged in the space surrounded by the energizing coil.

2. A contact device as claimed in claim 1 comprising two partly overlapping, parallel contact springs clamped tight in a hermetically closed envelope, characterized in that the energizing coil surrounds the hermetically closed envelope.

3. A contact device as claimed in claim 1 characterized in that the contact spring which is provided with a permanent magnet comprises a readily flexible portion which is located between the part of the contact spring provided with the permanent magnet and the part of the contact spring which is clamped tight.

4. A contact device as claimed in claim 1 wherein said countercontact comprises a second electrically conductive contact spring, a sealed envelope, said first and second contact springs beingclamped tight within said envelope at opposite ends of the envelope and extending parallel to one another and partly overlapping at their free ends, said coil surrounding the sealed envelope in the vicinity of the magnet. S 

1. A contact device comprising at least one electrically conductive contact spring clamped tight at one end and having its other freely movable end located opposite a countercontact, at least one energizing coil controlling the contact spring and having its field extending in the direction of length of the contact spring, at least one permanent magnet provided on the movable part of the contact spring near the clamped end and polarized transversely to the direction of length of the contact spring and adapted to be moved by the field of the energizing coil, said permanent magnet being arranged in the space surrounded by the energizing coil.
 2. A contact device as claimed in claim 1 comprising two partly overlapping, parallel contact springs clamped tight in a hermetically closed envelope, characterized in that the energizing coil surrounds the hermetically closed envelope.
 3. A contact device as claimed in claim 1 characterized in that the contact spring which is provided with a permanent magnet comprises a readily flexible portion which is located between the part of the contact spring provided with the permanent magnet and the part of the contact spring which is clamped tight.
 4. A contact device as claimed in claim 1 wherein said countercontact comprises a second electrically conductive contact spring, a sealed envelope, said first and second contact springs being clamped tight within said envelope at opposite ends of the envelope and extending parallel to one another and partly overlapping at their free ends, said coil surrounding the sealed envelope in the vicinity of the magnet. 